/*
 * Copyright (c) 2007-2012, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
package com.sun.org.apache.bcel.internal.classfile;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
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 *    notice, this list of conditions and the following disclaimer in
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 *    distribution.
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 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
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 *    "Apache BCEL" must not be used to endorse or promote products
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 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

import com.sun.org.apache.bcel.internal.Constants;
import java.io.*;

/**
 * This class represents the constant pool, i.e., a table of constants, of
 * a parsed classfile. It may contain null references, due to the JVM
 * specification that skips an entry after an 8-byte constant (double,
 * long) entry.  Those interested in generating constant pools
 * programatically should see <a href="../generic/ConstantPoolGen.html">
 * ConstantPoolGen</a>.

 * @see     Constant
 * @see     com.sun.org.apache.bcel.internal.generic.ConstantPoolGen
 * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
 */
public class ConstantPool implements Cloneable, Node, Serializable {
    private int constant_pool_count;
    private Constant[] constant_pool;

    /**
     * @param constant_pool Array of constants
     */
    public ConstantPool(Constant[] constant_pool) {
        setConstantPool(constant_pool);
    }

    /**
     * Read constants from given file stream.
     *
     * @param file Input stream
     * @throws IOException
     * @throws ClassFormatException
     */
    ConstantPool(DataInputStream file) throws IOException, ClassFormatException {
        byte tag;

        constant_pool_count = file.readUnsignedShort();
        constant_pool = new Constant[constant_pool_count];

        /* constant_pool[0] is unused by the compiler and may be used freely
         * by the implementation.
         */
        for (int i = 1; i < constant_pool_count; i++) {
            constant_pool[i] = Constant.readConstant(file);

            /* Quote from the JVM specification:
             * "All eight byte constants take up two spots in the constant pool.
             * If this is the n'th byte in the constant pool, then the next item
             * will be numbered n+2"
             *
             * Thus we have to increment the index counter.
             */
            tag = constant_pool[i].getTag();
            if ((tag == Constants.CONSTANT_Double) || (tag == Constants.CONSTANT_Long))
                i++;
        }
    }

    /**
     * Called by objects that are traversing the nodes of the tree implicitely
     * defined by the contents of a Java class. I.e., the hierarchy of methods,
     * fields, attributes, etc. spawns a tree of objects.
     *
     * @param v Visitor object
     */
    public void accept(Visitor v) {
        v.visitConstantPool(this);
    }

    /**
     * Resolve constant to a string representation.
     *
     * @param  constant Constant to be printed
     * @return String representation
     */
    public String constantToString(Constant c) throws ClassFormatException {
        String str;
        int i;
        byte tag = c.getTag();

        switch (tag) {
            case Constants.CONSTANT_Class:
                i = ((ConstantClass) c).getNameIndex();
                c = getConstant(i, Constants.CONSTANT_Utf8);
                str = Utility.compactClassName(((ConstantUtf8) c).getBytes(), false);
                break;

            case Constants.CONSTANT_String:
                i = ((ConstantString) c).getStringIndex();
                c = getConstant(i, Constants.CONSTANT_Utf8);
                str = "\"" + escape(((ConstantUtf8) c).getBytes()) + "\"";
                break;

            case Constants.CONSTANT_Utf8:
                str = ((ConstantUtf8) c).getBytes();
                break;
            case Constants.CONSTANT_Double:
                str = "" + ((ConstantDouble) c).getBytes();
                break;
            case Constants.CONSTANT_Float:
                str = "" + ((ConstantFloat) c).getBytes();
                break;
            case Constants.CONSTANT_Long:
                str = "" + ((ConstantLong) c).getBytes();
                break;
            case Constants.CONSTANT_Integer:
                str = "" + ((ConstantInteger) c).getBytes();
                break;

            case Constants.CONSTANT_NameAndType:
                str = (constantToString(((ConstantNameAndType) c).getNameIndex(), Constants.CONSTANT_Utf8) + " " + constantToString(((ConstantNameAndType) c).getSignatureIndex(), Constants.CONSTANT_Utf8));
                break;

            case Constants.CONSTANT_InterfaceMethodref:
            case Constants.CONSTANT_Methodref:
            case Constants.CONSTANT_Fieldref:
                str = (constantToString(((ConstantCP) c).getClassIndex(), Constants.CONSTANT_Class) + "." + constantToString(((ConstantCP) c).getNameAndTypeIndex(), Constants.CONSTANT_NameAndType));
                break;

            default: // Never reached
                throw new RuntimeException("Unknown constant type " + tag);
        }

        return str;
    }

    private static final String escape(String str) {
        int len = str.length();
        StringBuffer buf = new StringBuffer(len + 5);
        char[] ch = str.toCharArray();

        for (int i = 0; i < len; i++) {
            switch (ch[i]) {
                case '\n':
                    buf.append("\\n");
                    break;
                case '\r':
                    buf.append("\\r");
                    break;
                case '\t':
                    buf.append("\\t");
                    break;
                case '\b':
                    buf.append("\\b");
                    break;
                case '"':
                    buf.append("\\\"");
                    break;
                default:
                    buf.append(ch[i]);
            }
        }

        return buf.toString();
    }

    /**
     * Retrieve constant at `index' from constant pool and resolve it to
     * a string representation.
     *
     * @param  index of constant in constant pool
     * @param  tag expected type
     * @return String representation
     */
    public String constantToString(int index, byte tag) throws ClassFormatException {
        Constant c = getConstant(index, tag);
        return constantToString(c);
    }

    /**
     * Dump constant pool to file stream in binary format.
     *
     * @param file Output file stream
     * @throws IOException
     */
    public void dump(DataOutputStream file) throws IOException {
        file.writeShort(constant_pool_count);

        for (int i = 1; i < constant_pool_count; i++)
            if (constant_pool[i] != null)
                constant_pool[i].dump(file);
    }

    /**
     * Get constant from constant pool.
     *
     * @param  index Index in constant pool
     * @return Constant value
     * @see    Constant
     */
    public Constant getConstant(int index) {
        if (index >= constant_pool.length || index < 0)
            throw new ClassFormatException("Invalid constant pool reference: " + index + ". Constant pool size is: " + constant_pool.length);
        return constant_pool[index];
    }

    /**
     * Get constant from constant pool and check whether it has the
     * expected type.
     *
     * @param  index Index in constant pool
     * @param  tag Tag of expected constant, i.e., its type
     * @return Constant value
     * @see    Constant
     * @throws  ClassFormatException
     */
    public Constant getConstant(int index, byte tag) throws ClassFormatException {
        Constant c;

        c = getConstant(index);

        if (c == null)
            throw new ClassFormatException("Constant pool at index " + index + " is null.");

        if (c.getTag() == tag)
            return c;
        else
            throw new ClassFormatException("Expected class `" + Constants.CONSTANT_NAMES[tag] + "' at index " + index + " and got " + c);
    }

    /**
     * @return Array of constants.
     * @see    Constant
     */
    public Constant[] getConstantPool() {
        return constant_pool;
    }

    /**
     * Get string from constant pool and bypass the indirection of
     * `ConstantClass' and `ConstantString' objects. I.e. these classes have
     * an index field that points to another entry of the constant pool of
     * type `ConstantUtf8' which contains the real data.
     *
     * @param  index Index in constant pool
     * @param  tag Tag of expected constant, either ConstantClass or ConstantString
     * @return Contents of string reference
     * @see    ConstantClass
     * @see    ConstantString
     * @throws  ClassFormatException
     */
    public String getConstantString(int index, byte tag) throws ClassFormatException {
        Constant c;
        int i;

        c = getConstant(index, tag);

        /* This switch() is not that elegant, since the two classes have the
         * same contents, they just differ in the name of the index
         * field variable.
         * But we want to stick to the JVM naming conventions closely though
         * we could have solved these more elegantly by using the same
         * variable name or by subclassing.
         */
        switch (tag) {
            case Constants.CONSTANT_Class:
                i = ((ConstantClass) c).getNameIndex();
                break;
            case Constants.CONSTANT_String:
                i = ((ConstantString) c).getStringIndex();
                break;
            default:
                throw new RuntimeException("getConstantString called with illegal tag " + tag);
        }

        // Finally get the string from the constant pool
        c = getConstant(i, Constants.CONSTANT_Utf8);
        return ((ConstantUtf8) c).getBytes();
    }

    /**
     * @return Length of constant pool.
     */
    public int getLength() {
        return constant_pool_count;
    }

    /**
     * @param constant Constant to set
     */
    public void setConstant(int index, Constant constant) {
        constant_pool[index] = constant;
    }

    /**
     * @param constant_pool
     */
    public void setConstantPool(Constant[] constant_pool) {
        this.constant_pool = constant_pool;
        constant_pool_count = (constant_pool == null) ? 0 : constant_pool.length;
    }

    /**
     * @return String representation.
     */
    public String toString() {
        StringBuffer buf = new StringBuffer();

        for (int i = 1; i < constant_pool_count; i++)
            buf.append(i + ")" + constant_pool[i] + "\n");

        return buf.toString();
    }

    /**
     * @return deep copy of this constant pool
     */
    public ConstantPool copy() {
        ConstantPool c = null;

        try {
            c = (ConstantPool) clone();
        } catch (CloneNotSupportedException e) {
        }

        c.constant_pool = new Constant[constant_pool_count];

        for (int i = 1; i < constant_pool_count; i++) {
            if (constant_pool[i] != null)
                c.constant_pool[i] = constant_pool[i].copy();
        }

        return c;
    }
}
